Light source

ABSTRACT

An integrated light source includes: an emissive radiation source having a first spectrum; an optical element located to direct emissions from the emissive radiation source; a volumetric spectrum converter located to convert emissions directed from the emissive radiation source to emissions having a second spectrum different from the first spectrum; an optical reflector located about the converter; an output filter, the reflector being located to reflect the converter emissions towards the output filter; and a package body having an internal cavity containing the emissive radiation source, optical element, converter, reflector, and filter, wherein desired light radiates from the cavity through the filter.

BACKGROUND OF THE INVENTION

The present invention relates to solid state light emitting devices and,in particular, to those with a specified optical path and wavelengthoutput.

Prior solid-state lighting devices typically use a light emitting diode(LED), an organic light emitting diode (OLED), or a laser diode (LD) aspart of a remote phosphor system combined with one or more remotephosphors which convert a portion of the initial emitted radiation intoa usable spectrum. A remote phosphor system is a combination of areflective or transparent substrate, such as plastic, acrylic, glass,etc., that has a phosphorescent powder deposited on its surface. Thissubstrate can then convert the initial emitted light, usually blue orblue-violet coherent light, into broad spectrum non-coherent light,which is most commonly white light.

These devices already outperform incandescent and fluorescent lightsources with advantages that include longer lifetimes, energy savings,and brighter light output. However, while systems similar to thosedescribed above have been employed for some time, they still have issuesthat inhibit the technology. These issues include a low efficiencyconversion of the laser light, the non-conversion of some or most of thelaser light, the emission of dangerous coherent light, and thedifficulty of controlling the direction and optical path of the emittedconverted light.

For these reasons, the overall efficiency of the extant designs remainscomparatively low, even when LD-based devices (the most efficientdesign) are analyzed. Furthermore, prior designs that use an LD toprovide the primary light input completely saturate the remote phosphorelements. This over saturation can lead to the inadvertent emission ofcoherent laser light, which can cause damage to sensitive electronics,materials, eyes, and skin.

Thus, there is a need in the art for an improved solid state lightsource that has an extremely high operation and conversion efficiency,and is safe to use in multiple environments.

SUMMARY OF THE INVENTION

An integrated light source includes: an emissive radiation source havinga first spectrum; an optical element located to direct emissions fromthe emissive radiation source; a volumetric spectrum converter locatedto convert emissions directed from the emissive radiation source toemissions having a second spectrum different from the first spectrum; anoptical reflector located about the converter; an output filter, thereflector being located to reflect the converter emissions towards theoutput filter; and a package body having an internal cavity containingthe emissive radiation source, optical element, converter, reflector,and filter, wherein desired light radiates from the cavity through thefilter.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like reference numbers representcorresponding parts throughout:

FIG. 1 is a schematic diagram of a basic solid state light source systemaccording to the present invention;

FIG. 2 is a schematic diagram of another integrated light source thatutilizes multiple parts to enhance the efficiency and safety of thelight source, according to one embodiment of the present invention;

FIG. 3 is a schematic diagram that utilizes the integrated light sourceof FIG. 2 and illustrates a possible beam path for the light in thesystem, according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of the operation of a prior art phosphorcoated converter; and

FIG. 5 is a schematic diagram of the operation of an example volumetricspectrum converter according to an aspect of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

To overcome the limitations described above, and to overcome otherlimitations that will become apparent upon reading and understanding thepresent specification, a light source is disclosed that employs a solidstate light emitting device pumping a medium wherein phosphor isvolumetrically disposed. The light emitting device produces a beam oflight that is directed onto the phosphor and subsequently converted intoeither a broad- or narrow-spectrum light of desired wavelengths. Byutilizing a volumetrically disposed phosphor, a higher percentage of theincoming light can be converted, thus increasing the efficiency andsafety of the system. This converted light can then be sent over adesired optical path so as to control the final light output precisely.

Overview

To address these issues, a method for volumetrically disposingphosphorescent materials into a substrate has been invented. Thebenefits of a volumetrically disposed substrate over the current systemof using a thin coating are numerous and described herein. One of thebenefits is the increased conversion of laser light into non-coherentlight, which stems from the amount of phosphor available for lightconversion. The current thin surface coatings of phosphor get saturatedwith pre-converted light quickly and can only convert a small amount oflight at a time, greatly decreasing system efficiency. Attempting toincrease the amount of light-converting phosphor using the currenttechnology becomes extremely difficult as coherent light only travels inone direction, and thus requiring the layer of phosphor to eitherincrease in thickness, which impedes transmission and thereforeeffectiveness, or be distributed across a prohibitively large area.Using a volumetric deposition method allows for a larger amount ofphosphor to be utilized in converting coherent light, without creatingthe need for a larger emission beam of the coherent light. An increasein the amount of phosphor being utilized for conversion means that morenon-coherent light is produced with the same input; therefore the systemis more efficient. In addition, as more coherent light is converted tonon-coherent light, there is a decline in possibility that there will bedangerous coherent laser light emanating from the final light sourcesystem.

An advantageous embodiment of the invention can include one or moreoptical elements placed in specific arrangements to increase the overallefficiency of the system and decrease the potential of harmful coherentlight emissions. These elements include, but are not limited to,filters, lenses, a geometric optical reflector, and a housing. Theinclusion of one or more of the aforementioned optical elements allowsfor the modification and specialization of the solid state lightingsystem for specific instances and use cases.

DETAILED DESCRIPTION

Referring to FIG. 1, a solid state light source 100 is illustrated. Thelight source 100 includes a laser diode 101 in the form of asemiconductor laser disposed inside of a standard electronics componentpackage. The laser diode 101 has power pins 102 exiting the package. Thelaser diode 101 may, for example, provide coherent light within therange of 400-480 nm and, preferably, 430-470 nm. Beam 103 is thecoherent beam of laser light that the laser diode 101 produces. Beam 103strikes, and interacts with, volumetric spectrum converter 104 (e.g.,PMMA, which is volumetrically disposed with particles of phosphor).Converter 104 thusly converts the incoming coherent laser beam 103 intooutgoing broad spectrum light 105. The light 105 may be of any specifiedcolor, such as, but not limited to, white, and is decided by thechemical composition of the phosphor disposed in the medium 104.

Referring to FIG. 2, a possible design of an integrated light source 200is illustrated. The light source 200 includes an emissive radiationsource 202 having a first output spectrum, for example, in the form of asemiconductor laser diode disposed inside of a standard electronicscomponent package. The laser diode has power pins 203 exiting thepackage. Situated in front of the emission side of the emissiveradiation source 202 is an optical element 204 composed, for example, ofa lens, or system of lenses, that directs the coherent laser lightemitted from the laser diode 202 onto a specific area. The opticalelement 204 may, for example, collimate, convergently focus, ordivergently focus the emissions of the emissive radiation source 202 forconversion by the volumetric spectrum converter 205. The volumetricspectrum converter 205 converts the emissions from the emissiveradiation source 202 to emissions having a second spectrum differentthan the first spectrum. The volumetric spectrum converter 205 isdisposed inside of a geometric optical reflector 206 which is in thisembodiment, but is not limited to, a parabolic solid that directs thelight converted by the converter 205 towards a specified direction,which, in this case, is forward towards an output filter 207. After thelight has been directed forward by the optical reflector 206, the lightinteracts with the filter 207 which removes any coherent light that hasnot been converted into non-coherent light by the converting medium 205.Following this, only the filtered, non-coherent light can exit the lightsource 200 making the emitted light safe to use in multipleenvironments. Referring to the light source 200, all aforementionedcomponents are situated in an internal cavity 208 which is excised froma package body 201, which may be, for example, a piece of solid materialsuch as, but not limited to, aluminum, steel, or copper.

Referring to FIG. 3, a possible light path utilizing the light sourceseen in FIG. 2 is illustrated. The light source 300, which is comparableto the light source 200 of FIG. 2, includes a package body 301, which iscomparable to package body 201 of FIG. 2. Within the light source 300 ispositioned a laser diode 302 in the form of a semiconductor laserdisposed inside of a standard electronics component package. The laserdiode 302 emits a beam of coherent light 307 which proceeds to interactwith optical element 303. The optical element 303 redirects the coherentbeam 307 into a more precise path 308, which allows it to interact moreefficiently with the volumetric spectrum converter 304. The converter304 converts the coherent light 308 into non-coherent light 309 throughinternal physical interaction between the coherent light 308 with thevolumetrically disposed phosphor present in the converter 304.Subsequently the non-coherent light 309 is emitted in multipledirections from the converter 304. The non-coherent light 309 theninteracts with the geometric optical reflector 305. This opticalreflector 305 reflects the non-coherent multi-directional light 309 andredirects it forward 310. Most of the redirected light 310 passesthrough the filter 306 and leaves 311 the light source 300. Some of theredirected light 310 interacts with the filter 306 and is prevented 312from exiting the device for reasons such as design and safetyspecifications.

FIG. 4 illustrates a phosphor coated converter. The portion 401 is athinly deposited phosphor coating on a substrate 400. The thin phosphorcoating 401 has particles of phosphor 402 that are disposed within thecoating. The particles 402 convert light coming in from the right side403 into a different wavelength of light 404. Because the coating layer401 is thin, there is a limited amount of phosphor particles 402 thatcan convert the incoming light 403. Therefore, a large portion of theincoming light 403 is not converted, and leaves the substrate unaffected405.

FIG. 5 illustrates a volumetric spectrum converter, as opposed to thecoating in FIG. 4. In this case, the phosphor 501 is volumetricallydisposed within the substrate 500. This leads to more particles ofphosphor 502 that can interact with the incoming light 503, andtherefore participate in light conversion. Here there is a much largeramount of incoming light 503 that gets converted into the desiredwavelength 504. The use of a volumetric spectrum converter outperformsprior art phosphor coated converters.

It should be noted that this is a simplification for clarity. Theemitted light does not necessarily come out of the front all together.It is generally scattered omnidirectionally, and the reflectiveparaboloid (e.g., 206, 305) of the light source is what makes the lightgo in the same direction.

The optical reflector may be, for example, a molded, machined, 3-Dprinted or otherwise fabricated piece of optical material such as PMMA,polystyrene, polycarbonate, polyester, copolymers or blends of acombination of the aforementioned materials. It is designed to redirectomnidirectional light into a desired optical path. It may be, forexample, a solid geometric form, a hollow geometric form, or othercombinations of geometric surfaces. It may also advantageously include alayer of reflective material that enhances its capacity to redirectlight. This layer may be, for example, an external surface, an internalsurface, or a combination of surfaces.

The converter (e.g., 205, 304) may be chosen to convert emissions fromthe emissive radiation source (e.g., blue or violet light) to radiationof another wavelength, for example, narrow or broad spectrum,non-coherent radiation. It may be made using converting material thatmay include, for example, phosphorescent material, florescent material,other radiation converting material, or combinations of these materials.The converting material is volumetrically disposed in a substrate thatmay include, for example, PMMA, polystyrene, polycarbonate, polyester,copolymers or blends of a combination of the aforementioned materials tocreate an effectively homogenous composite. This process may include,for example, extrusion, coating, lamination, blending, mixing, orsuspending.

A particular example of making a converter is extruding a substrate withthe converting material as a blended and/or multilayered solidcomposite. In particular, the solid composite can be made with between 2and 500,000 layers which can be tuned for specified end use performancemetrics. It is desirable for the converter to not have any defects, suchas, for example, voids, entrapped gas, air bubbles, adulteratingparticulate of any material other the those purposely desired, orentrapped liquid of any sort, either vapor or liquid state, larger than1 micron.

The converter can possess a ratio of converting material, or acombination of multiple materials to the substrate, that can be tunedfor specified end use performance metrics.

In a preferred embodiment, the converting material may be of a singlephosphor with a particular particulate size, or a mix of phosphorpowders with either similar or dissimilar particulate sizes providing anemission of radiation that is either of a stable and/or variablewavelength. The emitted radiation can be for example, white light.

In another preferred embodiment, the converter possesses a ratio ofconverting material to the substrate between 5% and 15%.

It is also possible to tune the converter for specified end useperformance metrics by varying the thickness and diameter of theconverter. For example, a preferred embodiment includes a converter witha thickness of between 0.5 mm and 5 mm and a radius of between 0.5 mmand 5 mm.

The output filter (e.g., 207, 306) may be, for example, an opticallyclear window, but in the preferred embodiment, it eliminates any emittedradiation from the emissive radiation source that has not been convertedby the converter. It also may be, for example, a long-pass, short-pass,band-pass or band-stop filter to further pass or cutoff wavelengths ofradiation, to further condition the emitted light.

It should be further noted that the emissive geometry of the emittedradiation spectrum from the device may be further conditioned, directed,focused, collimated, reflected, refracted, diffracted, or otherwisemodified with the inclusion of suitable optical components.

The following are exemplary embodiments of the integrated light source.

Embodiment 1

An integrated light source comprising:

-   -   an emissive radiation source having a first spectrum;    -   an optical element located to direct emissions from said        emissive radiation source;    -   a volumetric spectrum converter, said converter being located to        convert emissions directed from said emissive radiation source        to emissions having a second spectrum different from said first        spectrum;    -   an optical reflector located about said converter;    -   an output filter, said reflector being located to reflect said        converter emissions towards said output filter; and

a package body having an internal cavity, said cavity containing saidemissive radiation source, optical element, converter, reflector, andfilter, wherein desired light radiates from said cavity through saidfilter.

Embodiment 2

A light source according to embodiment 1, wherein said radiation sourceoperates in the range of 400 nm to 480 nm.

Embodiment 3

A light source according to embodiment 1 or 2, wherein said radiationsource operates in the range of 430 nm to 470 nm.

Embodiment 4

A light source according to any of embodiments 1-3, wherein the opticalelement may either collimate, convergently focus, or divergently focusthe emissive radiation source emissions onto the converter.

Embodiment 5

A light source according to any of embodiments 1-4, wherein the opticalreflector redirects omnidirectional light into a desired optical path.

Embodiment 6

A light source according to any of embodiments 1-5, wherein the opticalreflector includes a layer of reflective material that enhances itscapacity to redirect light.

Embodiment 7

A light source according to any of embodiments 1-6, wherein theconverter converts the emissions from the emissive radiation source toemissions of different wavelength, a narrower spectrum, or a broaderspectrum, of non-coherent radiation.

Embodiment 8

A light source according to any of embodiments 1-7, wherein theconverter is composed of a converting material volumetrically disposedin a substrate of non-converting material to form a homogeneouscomposite.

Embodiment 9

A light source according to any of embodiments 1-8, wherein theconverter is created using a process that includes at least one ofextrusion, coating, lamination, blending, mixing, or suspending.

Embodiment 10

A light source according to any of embodiments 1-9, wherein the processof creating the converter is the extrusion of the substrate with theconverting material as a blended or multilayered solid composite.

Embodiment 11

A light source according to embodiment 9, wherein the solid compositehas a number of layers between 2 and 500,000.

Embodiment 12

A light source according to any of embodiments 1-11, wherein theconverter does not have any defects including voids, entrapped gas, airbubbles, adulterating particulate of any material other than thosepurposely desired, or entrapped liquid of any sort, either vapor orliquid state, larger than 1 micron.

Embodiment 13

A light source according to any of embodiments 1-12, wherein theconverter includes one or more phosphors, each with a particularparticulate size providing an emission of radiation that is of a stableor variable wavelength.

Embodiment 14

A light source according to any of embodiments 1-13, wherein theconverter possesses a ratio of one or more converting materials to thesubstrate that can be tuned for specified end use performance metrics.

Embodiment 15

A light source according to any of embodiments 1-14, wherein theconverter possesses a ratio of converting material to the substratebetween 5% and 15% by volume.

Embodiment 16

A light source according to any of embodiments 1-15, wherein theconverter possesses dimensions that can vary in thicknesses anddiameters which can be tuned for specified end use performance metrics.

Embodiment 17

A light source according to any of embodiments 1-16, wherein theconverter possesses a thickness between 0.5 mm and 5 mm and a radiusbetween 0.5 mm and 5 mm.

Embodiment 18

A light source according to any of embodiments 1-17, wherein the filtereliminates any emission from the emissive radiation source that has notbeen converted by the converter as well as optionally furtherconditioning the emitted light.

Embodiment 19

A light source according to any of embodiments 1-18, wherein theemissive geometry of the emitted radiation spectrum from the device maybe further conditioned, directed, focused, collimated, reflected,refracted, diffracted, or otherwise modified with the inclusion ofsuitable optical components.

It should be evident that this disclosure is by way of example and thatvarious changes may be made by adding, modifying or eliminating detailswithout departing from the fair scope of the teaching contained in thisdisclosure. The invention is therefore not limited to particular detailsof this disclosure except to the extent that the following claims arenecessarily so limited.

What is claimed is:
 1. An integrated light source comprising: an emissive radiation source emitting a first spectrum of radiation; an optical element located to direct the first spectrum of radiation from said emissive radiation source; a volumetric spectrum converter being located to convert the first spectrum of radiation directed from said emissive radiation source to a second spectrum of radiation different from said first spectrum of radiation, the volumetric spectrum converter including a plurality of layers forming a homogeneous composite substrate with a plurality of suspended particles volumetrically disposed within each of the plurality of layers of the homogeneous composite substrate, each of the plurality of suspended particles being configured to convert the first spectrum of radiation to the second spectrum of radiation; an optical reflector located about said volumetric spectrum converter; an output filter, said reflector being located to reflect said volumetric spectrum converter emissions towards said output filter; and a package body having an internal cavity, said cavity containing said emissive radiation source, optical element, volumetric spectrum converter, reflector, and output filter, wherein desired light radiates from said cavity through said output filter.
 2. The integrated light source according to claim 1, wherein said emissive radiation source operates in the range of 400 nm to 480 nm.
 3. The integrated light source according to claim 2, wherein said emissive radiation source operates in the range of 430 nm to 470 nm.
 4. The integrated light source according to claim 1, wherein the optical element may either collimate, convergently focus, or divergently focus the emissive radiation source emissions onto the volumetric spectrum converter.
 5. The integrated light source according to claim 1, wherein the optical reflector redirects omnidirectional light into a desired optical path.
 6. The integrated light source according to claim 5, wherein the optical reflector includes a layer of reflective material that enhances its capacity to redirect light.
 7. The integrated light source according to claim 1, wherein the volumetric spectrum converter converts the first spectrum of radiation from the emissive radiation source to emissions of different wavelength, a narrower spectrum, or a broader spectrum, of non-coherent radiation.
 8. The integrated light source according to claim 1, wherein the suspended particles are composed of a converting material and the homogeneous composite substrate is composed of a non-converting material.
 9. The integrated light source according to claim 1, wherein the volumetric spectrum converter is created using a process that includes at least one of extrusion, coating, lamination, blending, mixing, or suspending.
 10. The integrated light source according to claim 9, wherein the process of creating the volumetric spectrum converter is the extrusion of the homogeneous composite substrate with the converting material as a blended or multilayered solid composite.
 11. The integrated light source according to claim 10, wherein the solid composite has a number of layers between 2 and 500,000.
 12. The integrated light source according to claim 1, wherein the volumetric spectrum converter does not have any defects including voids, entrapped gas, air bubbles, adulterating particulate of any material other than those purposely desired, or entrapped liquid of any sort, either vapor or liquid state, larger than 1 micron.
 13. The integrated light source according to claim 1, wherein the volumetric spectrum converter includes one or more phosphors, each with a particular particulate size providing an emission of radiation that is of a stable or variable wavelength.
 14. The integrated light source according to claim 1, wherein the volumetric spectrum converter possesses a ratio of one or more converting materials to the homogeneous composite substrate that can be tuned for specified end use performance metrics.
 15. The integrated light source according to claim 14, wherein the volumetric spectrum converter possesses a ratio of converting material to the homogeneous composite substrate between 5% and 15% by volume.
 16. The integrated light source according to claim 1, wherein the volumetric spectrum converter possesses dimensions that can vary in thicknesses and diameters which can be tuned for specified end use performance metrics.
 17. The integrated light source according to claim 16, wherein the volumetric spectrum converter possesses a thickness between 0.5 mm and 5 mm and a radius between 0.5 mm and 5 mm.
 18. The integrated light source according to claim 1, wherein the output filter eliminates any of the first spectrum of radiation from the emissive radiation source that has not been converted by the volumetric spectrum converter as well as optionally further conditioning the emitted light.
 19. The integrated light source according to claim 1, wherein an emissive geometry of the emissions of the second spectrum may be further conditioned, directed, focused, collimated, reflected, refracted, diffracted, or otherwise modified with the inclusion of suitable optical components.
 20. The integrated light source according to claim 1, wherein the volumetric spectrum converter is optically coupled to the optical element and the optical element is positioned between the emissive radiation source and the volumetric spectrum converter.
 21. The integrated light source according to claim 1, wherein the homogeneous composite substrate includes one or more of poly(methyl methacrylate), polystyrene, polycarbonate, polyesters, copolymers, or combinations thereof. 